Wireless telemetry is used to support two-way communication between an IMD, such as an implantable pulse generator (IPG), implantable drug delivery device, or implantable sensing device, and another device, such as another IMD, an external medical device, or an external programmer, such as a patient or clinician programmer. For example, an external programmer may transmit information specifying adjustment of therapy parameters or operational features of the IMD. The transmitted information may include adjustments to therapy parameters, such as electrical stimulation pulse amplitude, pulse width, pulse rate, or duration, or drug delivery dosage, drug delivery rate, dosage limits, lockout intervals, or the like. In addition, transmitted information may include entire therapy programs, including parameter sets. Also, an IMD may transmit information to another IMD, an external medical device, or an external programmer, such as operational data, status data, diagnostic data, fault data, sensor data, or the like. Reliable telemetry is an important aspect of overall operation of an IMD.